Is it normal grandkids and my son are so snotty when i visit with my gf.

Every other year we visit my teenage grandkids and my son and his wife 2000 miles away. It is a nightmare. All they do is fight each other and us the whole time and they are very mean to my gf and I.They hate my gf for many reasons. She is a indian lady from england of a certain age.She don't take no bull from anyone and she gives me confidence to be a better person.She has me dressing better too. I feel alive again.They think I should have stayed alone after my wife died.It makes us upset and not feel well being treated so poor.Then they have the gall to ask for money and expensive gifts. My gf and I had a heated discussion about it. She thinks we shouldn't go where we aren't wanted.She is afraid I will have another heart attack or she will have a stroke or worse, she will get really steamed tell them all off. I have told them I am embarrassed they treat her so bad.I feel like a failure as a parent/grandparent.Her family is so nice to all of us.